With the rapid development of mobile communication technologies, it is often required in the construction of base station antenna arrays that the antenna array can not only cover multiple bands but also can support system with multiple wireless standards. When designing a dual-band or multi-band base station antenna arrays, especially broadband dual-band or multi-band antennas, the antennas usually have clutter outside the operating bands. These out-of-band clutter can cause serious coupling between different bands and can also seriously affect the antennas' pattern.
Traditional dual-band dual-polarized base station antenna arrays require cascade filters or combiners/duplexers for high out-of-band isolation. An invention patent application with publication number of CN 103036073, “Dual-band dual-polarized antenna”, adopts a scheme with cascade combiner to realize the isolation of antennas between two different bands. However, it will bring additional losses and increase the size and design complexity of the antenna. Another solution is to use a filter antenna, which combines the radiator and filter. The utility model patent with publication number of CN 202076403 discloses a dual-band dual-polarized antenna array loading with a filter. A quarter-wavelength branch is introduced on the feeder to achieve suppression of different bands, but it is only suitable for narrowband applications, but not broadband. The invention patent application with publication number of CN 105720364A from South China University of Technology “a dual-polarized filter antenna with high selectivity and low cross-polarization” realizes a highly selective filter antenna without extra filtering Unit. However, its selectivity is for adjacent bands that are close to the operating band. When the two operating bands are far apart and the bandwidth is relatively wide, it is difficult to work. The above dual-band base station arrays are nested antenna with high and low frequency, so only two columns of antenna performance can be achieved.